Systems and methods for coherence reduction in combustion system

ABSTRACT

A system includes a gas turbine engine having a first combustor and a second combustor. The first combustor includes a first set of fuel nozzles and a first plurality of injection pegs. The first plurality of injection pegs are disposed in a first configuration upstream of the first set of fuel nozzles, along a first fuel path, and the first plurality of injection pegs are configured to route a fuel to the first set of fuel nozzles. The system further includes a second combustor having a second set of fuel nozzles and a second plurality of injection pegs. The second plurality of injection pegs are disposed in a second configuration upstream of the second set of fuel nozzles, along a second fuel path, and the second plurality of injection pegs are configured to route the fuel to the second set of fuel nozzles. The second configuration has at least one difference relative to the first configuration.

BACKGROUND

The disclosed subject matter relates generally to gas turbine systems, and more particularly, to a system and method for controlling combustion dynamics, and more specifically, for reducing modal coupling of combustion dynamics.

Gas turbine systems generally include a gas turbine engine having a compressor section, a combustor section, and a turbine section. The combustor section may include one or more combustors (e.g., combustion cans) with fuel nozzles configured to inject a fuel and an oxidant (e.g., air) into a combustion chamber within each combustor. In each combustor, a mixture of the fuel and oxidant combusts to generate hot combustion gases, which then flow into and drive one or more turbine stages in the turbine section. Each combustor may generate combustion dynamics, which occur when the flame dynamics (also known as the oscillating component of the heat release) interact with, or excite, one or more acoustic modes of the combustor, to result in pressure oscillations in the combustor.

Combustion dynamics can occur at multiple discrete frequencies or across a range of frequencies, and can travel both upstream and downstream relative to the respective combustor. For example, the pressure and/or acoustic waves may travel downstream into the turbine section, e.g., through one or more turbine stages, or upstream into the fuel system. Certain downstream components of the turbine section can potentially respond to the combustion dynamics, particularly if the combustion dynamics generated by the individual combustors exhibit an in-phase and coherent relationship with each other, and have frequencies at or near the natural or resonant frequencies of the components. As discussed herein, “coherence” may refer to the strength of the linear relationship between two dynamic signals, and may be strongly influenced by the degree of frequency overlap between them. In some situations, “coherence” is a measure of the modal coupling, or combustor-to-combustor acoustic interaction, exhibited by the combustion system. Accordingly, a need exists to control the combustion dynamics, and/or modal coupling of the combustion dynamics, to reduce the possibility of any unwanted sympathetic vibratory response (e.g., resonant behavior) of components in the turbine system.

BRIEF DESCRIPTION

Certain embodiments commensurate in scope with the originally claimed invention are summarized below. These embodiments are not intended to limit the scope of the claimed invention, but rather these embodiments are intended only to provide a brief summary of possible forms of the invention. Indeed, the invention may encompass a variety of forms that may be similar to or different from the embodiments set forth below.

In a first embodiment, a system includes a gas turbine engine having a first combustor and a second combustor. The first combustor includes a first set of fuel nozzles and a first plurality of injection pegs. The first plurality of injection pegs are disposed in a first configuration upstream of the first set of fuel nozzles, along a first fuel path, and the first plurality of injection pegs are configured to route a fuel to the first set of fuel nozzles. The system further includes a second combustor having a second set of fuel nozzles and a second plurality of injection pegs. The second plurality of injection pegs are disposed in a second configuration upstream of the second set of fuel nozzles, along a second fuel path, and the second plurality of injection pegs are configured to route the fuel to the second set of fuel nozzles. The second configuration has at least one difference relative to the first configuration.

In a second embodiment, a system includes a first turbine combustor. The first combustor includes a first plurality of fuel nozzles configured to route an air-fuel mixture to a combustion chamber of the first turbine combustor. The first plurality of fuel nozzles comprises a first set of fuel nozzles and a second set of fuel nozzles. The system also includes a first plurality of injection pegs configured to route a fuel to the first plurality of fuel nozzles. The first plurality of injection pegs comprises a first set of injection pegs associated with the first set of fuel nozzles and a second set of injection pegs associated with the second set of fuel nozzles. The first set of injection pegs has at least one difference relative to the second set of injection pegs.

In a third embodiment, a method includes controlling a first combustion dynamic of a first combustor or a first convective time of a first set of injection pegs of the first combustor with a first configuration of a first plurality of injection pegs disposed upstream of the first set of fuel nozzles along a first fuel path. The method further includes controlling a second combustion dynamic of a second combustor or a second convective time of a second set of injection pegs of the second combustor with a second configuration of a second plurality of injection pegs disposed upstream of the second set of fuel nozzles along a second fuel path. The second plurality of injection pegs has at least one difference relative to the first plurality of injection pegs.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic of an embodiment of a gas turbine system having a plurality of combustors with a respective fuel circuit configuration configured to control combustion dynamics and/or modal coupling of combustion dynamics to reduce the possibility of unwanted vibratory responses in downstream components;

FIG. 2 is a cross-sectional schematic of an embodiment of one of the combustors of FIG. 1, wherein the combustor includes a first quaternary fuel circuit configuration with an axial staggering of injection pegs;

FIG. 3 is a cross-sectional schematic of an embodiment of one of the combustors of FIG. 1, wherein the combustor includes a second quaternary fuel circuit configuration with a circumferential arrangement of injection pegs;

FIG. 4 is a cross-sectional schematic of an embodiment of the combustor of FIG. 3 taken along line 4-4, illustrating a plurality of quat pegs arranged around an axis and biased to a first fuel circuit; and

FIG. 5 is a cross-sectional schematic of an embodiment of the gas turbine system of FIG. 1, taken along line 5-5, illustrating a plurality of combustors with respective quaternary fuel circuit configurations configured to control combustion dynamics and/or modal coupling of combustion dynamics to reduce the possibility of unwanted vibratory responses in downstream components.

DETAILED DESCRIPTION

One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

The disclosed embodiments are directed toward reducing combustion dynamics and/or modal coupling of combustion dynamics (e.g., reduce unwanted vibratory responses in downstream components) in a gas turbine system by varying a fuel circuit configuration, such as the configuration of a quaternary fuel circuit or manifold. In particular, the disclosed embodiments are directed towards varying the configuration of a plurality of injection pegs (e.g., quat pegs) within one or more quaternary fuel circuits associated with one or more combustors of the gas turbine system, such that the arrangement of the quat pegs are configured to reduce combustion dynamics and/or unwanted vibratory responses within the system.

As noted above, a gas turbine combustor (or combustor assembly) may generate combustion dynamics due to the combustion process, characteristics of intake fluid flows (e.g., fuel, oxidant, diluent, etc.) into the combustor, and various other factors. The combustion dynamics may be characterized as pressure fluctuations, pulsations, oscillations, and/or waves at certain frequencies. The fluid flow characteristics may include velocity, pressure, fluctuations in velocity and/or pressure, variations in flow paths (e.g., turns, shapes, interruptions, etc.), or any combination thereof. Collectively, the combustion dynamics can potentially cause vibratory responses and/or resonant behavior in various components upstream and/or downstream from the combustor. For example, the combustion dynamics (e.g., at certain frequencies, ranges of frequencies, amplitudes, combustor-to-combustor phases, etc.) can travel both upstream and downstream in the gas turbine system. If the gas turbine combustors, upstream components, and/or downstream components have natural or resonant frequencies that are driven by these pressure fluctuations (e.g., combustion dynamics), then the pressure fluctuations can potentially cause vibration, stress, fatigue, etc. The components may include combustor liners, combustor flow sleeves, combustor caps, fuel nozzles, turbine nozzles, turbine blades, turbine shrouds, turbine wheels, bearings, fuel supply assemblies, or any combination thereof. The downstream components are of specific interest, as they are more sensitive to combustion tones that are in-phase and coherent. Thus, reducing coherence specifically reduces the possibility of unwanted vibrations in downstream components.

As discussed in detail below, the disclosed embodiments may equip one or more gas turbine combustors with a particular fuel circuit arrangement (e.g., quaternary fuel circuit arrangement) configured to modify the combustion dynamics of the gas turbine combustor, e.g., varying the frequency, amplitude, combustor-to-combustor coherence, range of frequencies, or any combination thereof. In particular, the arrangement of a plurality of quaternary pegs or quat pegs (e.g., injection pegs) of each quaternary fuel circuit system associated with a particular combustor may alter the convective time for one or more quat pegs, and/or fuel-air ratio at the nozzle level, which may alter the combustion dynamics, in a way to substantially reduce or eliminate any unwanted vibratory response of components upstream and/or downstream of the turbine combustor, as well as the gas turbine combustors. Varying the fuel-air ratio at the nozzle level may modify the distribution of the heat release, which alters the flame dynamics, and therefore the combustion dynamics. In addition, convective time is an important factor in combustion dynamics frequencies and/or amplitudes. The convective time refers to the delay between the time that the fuel is injected through the fuel ports of the gas turbine combustor and the time when the fuel reaches the combustion chamber and ignites. Altering the axial position of the quat pegs, alters the travel time for the fuel between the quat pegs and the flame zone, and therefore alters the convective time. Generally, there is an inverse relationship between convective time and frequency. That is, when the convective time increases, the frequency of the combustion instability decreases, and when the convective time decreases, the frequency of the combustion instability increases. In addition, varying the convective time between the quat pegs may encourage destructive interference of the combustion dynamics generated by, or contributed to, by the quat pegs, which may reduce the amplitudes of the combustion dynamics and/or alter the frequency of the combustion dynamics. For example, varying the configuration (e.g., placement, arrangement, position, location, etc.) of quat pegs axially and/or circumferentially around the head end of the combustor may facilitate the tuning of convective time for one or more quat pegs, and/or the fuel-air ratio at the nozzle level, and may result in combustion dynamics with reduced amplitudes, and/or frequencies that are different, and/or spread out over a greater frequency range, or any combination thereof, relative to any resonant frequencies of the components in the gas turbine system. In addition, varying the geometries of the quat pegs (e.g., size, shape, angle, etc.) may introduce a variation in convective time for one or more quat pegs, and/or fuel-air ratio at the nozzle level, and may result in combustion dynamics with reduced amplitudes, and/or frequencies that are different and/or spread out over a greater frequency range, relative to any resonant frequencies of the components in the gas turbine system.

In addition to modifications on a combustor level (i.e., individual turbine combustor), the disclosed embodiments may vary the configuration (e.g., arrangement, location, position, etc.) and/or the geometry (e.g., angle, size, shape, etc.) of the quat pegs within each quaternary fuel circuit among a plurality of gas turbine combustors, thereby varying the combustion dynamics, from combustor-to-combustor, in a manner to reduce the combustion dynamics amplitudes and/or modal coupling of the combustion dynamics among the plurality of gas turbine combustors. For example, varying the configuration of the quat pegs (e.g., placement, location, position, arrangement, etc.) axially and/or circumferentially between or among combustors of the system may result in combustor-to-combustor variations in the combustion dynamics frequencies (e.g., frequencies that are different, spread out over a greater frequency range, or any combination thereof), thereby reducing the possibility of modal coupling of the combustors, particularly at frequencies that are aligned with resonant frequencies of the components of the gas turbine system. Likewise, the geometries of the quat pegs (e.g., size, shape, angle, etc.) may be varied between or among combustors of the system to help reduce unwanted vibratory responses.

With the forgoing in mind, FIG. 1 is a schematic of an embodiment of a gas turbine system 10 having a plurality of combustors 12, where each combustor 12 is associated with one or more quaternary fuel circuits 13 (e.g., quat fuel circuit 13). Each quat fuel circuit 13 may include a plurality of quaternary pegs 14 (e.g., injection pegs, quat pegs), where each quat peg 14 may be configured to inject fuel into the combustor 12 upstream of the fuel nozzles 18 in the combustor 12. For example, each quat fuel circuit 13 may include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more quat pegs 14 that are arranged around the circumference of the combustor 12 upstream of the fuel nozzles 18 (e.g., primary fuel nozzles 18). The configuration and/or the geometries of the quat pegs 14 of each quat fuel circuit 13 may be varied within and/or among the combustors 12 to change the combustion dynamics in a particular combustor 12 and/or between the combustors 12, thereby helping to reduce any unwanted vibratory responses in components downstream of the system 10, as will be further described in detail below. Specifically, varying the configuration and/or the geometries of the quat pegs 14 within the combustor 12 and/or among the combustors 12 may vary the convective time between the quat pegs, and/or fuel-air ratio between the fuel nozzles 18 associated with the quat pegs 14, thereby decreasing combustion dynamics amplitudes and/or varying the combustion dynamics frequencies within a particular combustor 12, and/or between adjacent combustors 12, and/or among a plurality of combustors 12, which is expected to reduce the coherence of the combustors 12, as further described in detail below.

In the illustrated embodiment, the gas turbine system 10 includes one or more combustors 12 each having the quat fuel circuit 13, a compressor 11, and a turbine 16. Each quat fuel circuit 13 may include one or more quat pegs 14, which may be configured to direct a fuel from one or more fuel sources into the combustor 12 upstream of one or more fuel nozzles 18 (e.g., 1, 2, 3, 4, 5, 6, or more) within the combustor 12. The combustors 12 ignite and combust a pressurized oxidant (e.g., air) and fuel mixture (e.g., an air-fuel mixture) within the combustion chambers 19, and then pass resulting hot pressurized combustion gases 24 (e.g., exhaust) into the turbine 16. In certain embodiments, the fuel nozzles 18 may grouped into one or more primary fuel circuits (e.g., 1, 2, 3, 4, 5, or more fuel circuits), where each primary fuel circuit includes one or more fuel nozzles 18. Each primary fuel circuit may be associated with a fuel source. The fuel nozzles 18 associated with one or more primary fuel circuits may also be associated with one or more quat pegs 14, i.e. one or more quat pegs 14 may inject fuel into the flow passage 64 (as shown in FIG. 2), where it mixes with the airflow 67 from the compressor discharge 68 (as shown in FIG. 2), prior to entering one or more fuel nozzles 18 associated with one or more fuel circuits, creating a fuel-air mixture that then enters the fuel nozzles 18, where additional fuel will be injected by the fuel nozzles 18. In certain embodiments, varying the configuration and/or geometries of the quat pegs 14 may tune the convective time of one or more quat pegs and/or the air/fuel ratio of the one or more fuel nozzles 18 associated with the quat pegs 14, thereby altering the combustion dynamics amplitudes and/or frequencies within the combustor 12 and/or among the combustors 12 of the system 10.

In particular, varying the configuration and/or geometries of the quat pegs 14 may vary convective time for one or more quat pegs, and/or fuel-air ratio for one or more fuel nozzles 18. Accordingly, varying the convective time for one or more quat pegs, and/or fuel-air ratio of one or more fuel nozzles 18 via the configuration and/or geometries of the quat pegs 14 may modify the resulting combustion dynamics of the combustor 12 and/or among the combustors 12 of the system 10. Modifying the combustion dynamics, in turn, may reduce the possibility of unwanted vibratory responses in the combustor 12, and/or downstream components. For example, in certain embodiments, the combustors 12 of the system 10 may be identical except for variations in the configuration and/or geometries of the quat pegs 14 within each combustor 12. Accordingly, the variations in the configuration and/or geometries of the quat pegs 14 between the combustors 12 may help modify or reduce modal coupling of the combustion dynamics between the combustors 12.

Turbine blades within the turbine 16 are coupled to a shaft 26 of the gas turbine system 10, which may also be coupled to several other components throughout the turbine system 10. As the combustion gases 24 flow against and between the turbine blades of the turbine 16, the turbine 16 is driven into rotation, which causes the shaft 26 to rotate. Eventually, the combustion gases 24 exit the turbine system 10 via an exhaust outlet 28. Further, in the illustrated embodiment, the shaft 26 is coupled to a load 30, which is powered via the rotation of the shaft 26. The load 30 may be any suitable device that generates power via the torque of the turbine system 10, such as an electrical generator, a propeller of an airplane, or other load.

The compressor 11 of the gas turbine system 10 includes compressor blades. The compressor blades within the compressor 11 are coupled to the shaft 26, and will rotate as the shaft 26 is driven to rotate by the turbine 16, as discussed above. As the compressor blades rotate within the compressor 11, the compressor 11 compresses air (or any suitable oxidant) received from an air intake 32 to produce pressurized air 34. The pressurized air 34 is then fed into the fuel nozzles 18 of the combustors 12. As mentioned above, the fuel nozzles 18 mix the pressurized air 34 and fuel to produce a suitable mixture ratio for combustion. In the following discussion, reference may be made to an axial direction or axis 42 (e.g., a longitudinal axis) of the combustor 12, a radial direction or axis 44 of the combustor 12, and a circumferential direction or axis 46 of the combustor 12.

In certain embodiments, varying the configuration of the quat pegs 14 of the quat fuel circuit 13 axially and/or circumferentially and/or varying the geometries of the quat peg 14 (e.g., shapes, sizes, angles, etc.) may help reduce unwanted vibratory responses within the combustor 12 and/or downstream turbine components in the system 10. For example, in the illustrated embodiment, the system 10 includes a first combustor 17 associated with a first quat fuel circuit 13 and a second combustor 21 associated with a second quat fuel circuit 13. Each quat fuel circuit 13 may be associated with a plurality of quat pegs 14 configured to route the fuel and/or the air/fuel mixture to the fuel nozzles 18. In certain embodiments, the configuration of the plurality of quat pegs 14 associated with a particular combustor 12 may be different than the configuration of the plurality of quat pegs 14 associated with an adjacent or non-adjacent combustor 12. For example, a first set of quat pegs 14 associated with the first combustor 17 may be disposed approximately along a first axis 48 along the circumferential direction 46 of the system 10. In the illustrated embodiment, a second set of quat pegs 15 associated with the second combustor 21 may be disposed approximately along a second axis 50 approximately parallel to the first axis 48. In particular, the second set of quat pegs 15 may be axially staggered relative to the first set of quat pegs 14, such that a first configuration of the quat pegs 14 is different from a second configuration of the quat pegs 15.

While the illustrated embodiment depicts varying the configuration of the quat pegs 14 via axial staggering of the quat pegs 14 between adjacent combustors 12 of the system 10, it should be noted that the configuration of the quat pegs 14 may be varied by axially staggering the quat pegs 14 between 2, 3, 4, 5, 6, or more combustors 12 within the system 10 along 1, 2, 3, 4, 5, 6, or more axial positions along the circumferential direction 46. In certain embodiments, the configuration of the quat pegs 14 may be varied within a particular combustor 12 (as further described in FIG. 2), by axially staggering the quat pegs 14 along 1, 2, 3, 4, 5, 6 or more axial positions along the circumferential direction 46 within the particular combustor 12. In addition, in certain embodiments, it should be noted that the configuration of the quat pegs 14 among one or more combustors 12 may be varied by circumferentially distributing the quat pegs 14 in various configurations, as further described with respect to FIGS. 3-5.

FIG. 2 is a cross-sectional schematic of an embodiment of the combustor 12 in the system 10 of FIG. 1, wherein the combustor 12 includes a first quaternary fuel circuit configuration where the quat pegs 14 (e.g., injection pegs) are staggered axially, at 1, 2, 3, 4, 5, 6 or more axial positions along the circumferential direction 46. As noted above with respect to FIG. 1, the configurations of the quat pegs 14 may be varied by axially staggering the quat pegs 14 among one or more combustors 12 at one or more axial positions 48, 50. In the illustrated embodiment, the quat pegs 14 are varied within a single combustor 12, such that the quat pegs 14 are axially staggered along the first axial position 48, the second axial position 50, and a third axial position 52 along the circumferential direction 46 of the system 10. As noted above, varying the configuration and/or geometries of the quat pegs 14 within the combustor 12 may vary the convective time for one or more quat pegs, and/or the fuel-air ratio of the fuel nozzles 18 associated with the quat pegs 14, thereby decreasing combustion dynamics amplitudes within the combustor, which is expected to reduce unwanted vibratory responses within the gas turbine system 10.

In the illustrated embodiment, the combustor 12 includes a head end 54 and the combustion chamber 19. The head end 54 of the combustor 12 generally encloses a cap assembly 56 and the fuel nozzles 18, such as 1, 2, 3, 4, 5, 6, 7 or more fuel nozzles 18. In certain embodiments, the fuel nozzles 18 route fuel, air, fuel-air mixtures, and sometimes other fluids to the combustion chamber 19. In particular, the fuel nozzles 18 may be grouped or arranged into one or more different fuel circuits, such that each fuel circuit contains one or more fuel nozzles 18 and where each fuel circuit may route a fuel and/or an air/fuel mixture from one or more fuel sources. The combustor cap assembly 56 is disposed along a portion of the length of the fuel nozzles 18, housing the fuel nozzles 18 within the combustor 12. Each fuel nozzle 18 facilitates the mixing of pressurized air and fuel and directs the mixture through the combustor cap assembly 56 and into the combustion chamber 19. The air-fuel mixture may then combust in a primary combustion zone 57 of the chamber 19, thereby creating hot pressurized exhaust gases that flow in a downstream direction 69. These pressurized exhaust gases drive the rotation of blades within the turbine 16. The combustor 12 has one or more walls extending circumferentially 46 around the combustion chamber 19 and the axis 42 of the combustor 12, and generally represents one of a plurality of combustors 12 that are disposed in a spaced arrangement circumferentially about a rotational axis (e.g., shaft 26) of the gas turbine system 10.

Each combustor 12 includes an outer wall (e.g., flow sleeve 58) disposed circumferentially about an inner wall (e.g., combustor liner 60) to define an intermediate flow passage or space 64, while the combustor liner 60 extends circumferentially about the combustion chamber 19. The inner wall 60 also may include a transition piece 66, which generally converges toward a first stage of the turbine 16. The impingement sleeve 59 is disposed circumferentially about the transition piece 66. The liner 60 defines an inner surface of the combustor 12, directly facing and exposed to the combustion chamber 19. The flow sleeve 58 and impingement sleeve 59 include a plurality of perforations 61, which direct an airflow 67 from a compressor discharge 68 into the flow passage 64 while also impinging air against the liner 60 and the transition piece 66 for purposes of impingement cooling. The flow passage 64 then directs the airflow 67 in an upstream direction toward the head end 54 (e.g., relative to a downstream direction 69 of the hot combustion gases), such that the airflow 67 further cools the liner 60 before flowing through the combustor cap assembly 56, through the fuel nozzles 18, and into the combustion chamber 19.

In certain embodiments, the combustor 12 may include the quaternary fuel circuit 13 having a plurality of quat pegs 14 in various configurations and/or geometries. Specifically, the quat pegs 14 may be disposed circumferentially around the combustor 12 near the head end 54. In certain embodiments, the airflow 67 flowing through the combustor cap assembly 56 may encounter the quat pegs 14 associated with the fuel nozzles 18. Specifically, the quat pegs 14 may be configured as fuel injectors that inject a portion of a fuel into the airflow 67 upstream of the fuel nozzles 18. In particular, one or more quat pegs 14 may be associated with one or more respective fuel nozzles 18. In certain embodiments, each fuel nozzle 18 may be associated with one or more quat pegs 14. Further, in some embodiments, one or more quat pegs 14 may be associated with a group of fuel nozzles 18, such as a group of fuel nozzles 18 within a particular fuel circuit, as further explained with respect to FIG. 5. The fuel injected by the quat pegs 14 may be provided by one or more fuel sources coupled to the quat fuel circuit 13 via a fuel manifold. In certain embodiments, the quat pegs 14 may include one or more fuel openings (not shown) facing and/or angled approximately perpendicular to the downstream direction 69 of the combustor 12. The fuel provided by the quat pegs 14 may mix with the airflow 67 flowing towards the fuel nozzles 18 to form an air/fuel mixture that is then routed to the combustion chamber 19 via the fuel nozzles 18.

As noted above, varying the configuration (e.g., position, location, arrangement, placement, axial staggering, circumferential variations, etc.) and/or geometries (e.g., sizes, shapes, angles, etc.) of the quat pegs 14 among combustors 12 may vary the convective time for one or more quat pegs, and/or the fuel-air ratio of the fuel nozzles 18 associated with the quat pegs 14 among the combustors 12, thereby decreasing combustion dynamics amplitudes, and/or varying combustion dynamics frequencies among the combustors, which is expected to reduce modal coupling of combustion dynamics. For example, in the illustrated embodiment of the combustor 12, a first set of quat pegs 14 are disposed approximately along the first axial position 48, a second set of quat pegs 15 are disposed approximately along the second axial position 50, and a third set of quat pegs 23 are disposed approximately along the third axial position 52, such that each set of quat pegs 14, 15, and 23 are axially staggered proximal to the head end 54 and around the circumference of the combustor 12. Each set of quat pegs 14 may include 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more quat pegs 14 configured to route a fuel toward one or more particular fuel nozzles 18. In some embodiments, axially staggering the quat pegs 14 may vary the convective time for one or more quat pegs, and/or may vary the air/fuel ratio of one or more fuel nozzles 18. For example, in the illustrated embodiment, the air/fuel ratio of the one or more fuel nozzles 18 associated with the first set of quat pegs 14 (having 3 quat pegs 14) may be different than the air/fuel ratio of the one or more fuel nozzles 18 associated with the third set of quat pegs 14 (having 4 quat pegs 14), thereby varying the combustion dynamics of the combustor 12 to reduce unwanted vibratory response within the combustor and/or in downstream components.

While the illustrated embodiment depicts each set of quat pegs 14, 15, and 23 with approximately the same size and/or shape, it should be noted that in some embodiments, each quat peg 14 and/or each set of quat pegs 14, 15, or 23 may be a different geometry (e.g., size, shape, angle, etc.). For example, in certain embodiments, the first set of quat pegs 14 may be different in size relative to the second set of quat pegs 15 (e.g., ratio of 1:1, 1.5:1, 2:1, 2.5:1, etc.). Likewise, the first set of quat pegs 14 may be different in shape relative to the second set of quat pegs 15 (e.g., square, conical, etc.), approximately, or may be at different angles relative to the second set of quat pegs 15, thereby varying the combustion dynamics of the combustor 12 to reduce unwanted vibratory response in the gas turbine system 10. For example, the quat pegs 14 may include one or more fuel openings (not shown) facing and/or angled approximately perpendicular to the downstream direction 69 of the combustor 12. In certain embodiments, the angle of the fuel openings to the downstream direction 69 on a particular quat peg 14 may be different (e.g., greater than or less than) compared to the angle of the fuel openings to the downstream direction 69 on another quat peg 14 (e.g., approximately 1, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180 degrees more or less). In other embodiments, the entire quat peg 14 may be angled approximately perpendicular to the downstream direction 69, such that the angle of a particular quat peg 14 is different from the angle of another quat peg 14 (e.g., approximately 1, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180 degrees more or less).

In some embodiments, the configuration of the quat pegs 14 may be varied within a particular combustor 12 at a single axial position (e.g., the first axial position 48, the second axial position 50, or the third axial position 52), by circumferentially distributing the quat pegs 14 along a particular axial position in the circumferential direction 46 in various configurations, as further described with respect to FIG. 3. Further, in some embodiments, the configuration of the quat pegs 14 may be varied between adjacent combustors 12 and/or among a plurality of combustors 12 within the system 10 by circumferentially distributing the quat pegs 14 at a particular axial position in various configurations differently in one combustor 12 compared to at least one other combustor 12, as further described with respect to FIG. 5.

FIG. 3 is a cross-sectional schematic of an embodiment of the combustor 12 in the system 10 of FIG. 1, wherein the combustor 12 includes a second quaternary fuel circuit configuration having a circumferential distribution (i.e. along the circumferential axis 46) of the quat pegs 14 (e.g., injection pegs) at a particular axial position. For example, in the illustrated embodiment, a fourth set of quat pegs 25 comprising five quat pegs 14 and a fifth set of quat pegs 27 comprising three quat pegs 14 are circumferentially disposed (e.g., arranged, configured, etc.) approximately along the second axial position 50 along the circumferential axis 46. In particular, each set of quat pegs 25, 27 may be configured to route a fuel to one or more particular fuel nozzles 18 and/or a particular group of fuel nozzles 18 (e.g., a fuel circuit comprising one or more fuel nozzles 18). As noted above, varying the configuration of the quat pegs 14 within the combustor 12 may vary the convective time of one or more quat pegs 14 and/or vary the fuel-air ratio of one or more fuel nozzles 18 associated with one or more quat pegs 14, thereby decreasing coherence and reducing unwanted vibratory responses within the combustor 12 as well as in downstream components.

In some embodiments, the quat pegs 14 may be approximately disposed at a single axial position (e.g., the second axial position 50), such that the quat pegs 14 are circumferentially arranged in various configurations and associated with various fuel nozzles 18 and/or various groups of fuel nozzles 18 (e.g., fuel circuits comprising one or more fuel nozzles 18). For example, in the illustrated embodiment, the fourth set 25 of quat pegs 14 comprising five quat pegs 14 may be spatially disposed and/or grouped away from the fifth set 27 of quat pegs 14 comprising three quat pegs 14. In such embodiments, each set of the quat pegs 14 (e.g., the fourth set 25 and/or the fifth set 27) may be associated with one or more fuel nozzles 18, such as a single fuel nozzle 18 and/or a group of fuel nozzles 18 grouped into a single fuel circuit, as further described with respect to FIG. 4. Each set of quat pegs 14 may include 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more quat pegs 14 configured to increase or decrease the fuel-air ratio for a particular fuel nozzle 18 or a particular group of fuel nozzles 18. In some embodiments, circumferentially disposing the quat pegs 14 at a particular axial position in various circumferential configurations may vary the air-fuel ratio of the one or more fuel nozzles 18 associated with one or more quat pegs 14. For example, in the illustrated embodiment of FIG. 3, the air/fuel ratio of the fuel nozzles 18 associated with the fourth set of quat pegs 25 (having 5 quat pegs 14) may be different than the air-fuel ratio of the one or more fuel nozzles 18 associated with the fifth set of quat pegs 27 (having 3 quat pegs 14). Further, the air-fuel ratio of the one or more fuel nozzles not associated with either the fourth set of quat pegs 25 or the fifth set of quat pegs 27 may also be different, thereby varying the combustion dynamics of the combustor 12 to reduce unwanted vibratory response, either within the combustor 12 or within downstream components.

In some embodiments, in addition to various quat peg 14 configurations (e.g., circumferential arrangements at a particular axial position 48, 50, or 52), each quat peg 14 and/or each set of quat pegs 25 or 27 may have a different geometry (e.g., size, shape, angle, etc.). For example, in certain embodiments, the fourth set of quat pegs 25 may be different in size relative to the fifth set of quat pegs 25 (e.g., ratio of approximately 1:1, 1.5:1, 2:1, 2.5:1, etc.), such that one or more quat pegs 14 from the fourth set 25 is greater than or less than the size of one or more quat pegs 14 from the fifth set 27. Likewise, the fourth set of quat pegs 25 may be different in shape relative to the fifth set of quat pegs 25 (e.g., square, conical, etc.), or may have different angles relative to the fifth set of quat pegs 27, thereby varying the combustion dynamics of the combustor 12 to reduce unwanted vibratory response, either within the combustor 12 or within downstream components. For example, the quat pegs 14 may include one or more fuel openings (not shown) facing and/or angled approximately perpendicular to the downstream direction 69 of the combustor 12. In certain embodiments, the angle of the fuel openings to the downstream direction 69 on a particular quat peg 14 may be greater than or less than the angle of the fuel openings to the downstream direction 69 on another quat peg 14 (e.g., approximately 1, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180 degrees more or less).

FIG. 4 is a cross-sectional schematic of an embodiment 69 of the combustor 12 of FIG. 3, illustrating the quat pegs 14 arranged circumferentially at the second axial position 50 and biased to a first fuel circuit 72. In certain embodiments, the combustor 12 may include four or more fuel circuits, such as the first fuel circuit 72, a central fuel circuit 74, a second fuel circuit 76, and one or more quat fuel circuits 13. Specifically, the first fuel circuit 72 may comprise three fuel nozzles 18 (e.g., a first fuel nozzle 73, a second fuel nozzle 75, and a third fuel nozzle 77). In addition, the central fuel circuit 74 may comprise a single fuel nozzle, and the second fuel circuit 76 may comprise two fuel nozzles 18 (e.g., a fourth fuel nozzle 79 and a fifth fuel nozzle 81). In particular, each fuel nozzle 18 and/or each fuel circuit (e.g., the first fuel circuit 72, the central fuel circuit 74, or the second fuel circuit 76) may be associated with one or more quat pegs 14 configured to route the fuel to the respective fuel nozzle 18 and/or the respective fuel circuit (e.g., one or more fuel nozzles 18). Accordingly, the quat pegs 14 may be configured to vary the air/fuel ratio of the fuel nozzles 18 and/or the fuel circuits associated with the quat pegs 14, thereby decreasing coherence and reducing unwanted vibratory responses within the combustor 12 and/or downstream components.

In some embodiments, the plurality of quat pegs may be associated with one or more fuel nozzles 18 of the combustor 12. For example, in the illustrated embodiment, the fourth set of quat pegs 25 and the fifth set of quat pegs 27 are associated with the first fuel circuit 72. Specifically, the fourth set of quat pegs 25 and the fifth set of quat pegs 27 may be associated with the first fuel nozzle 73, the second fuel nozzle 75, and the third fuel nozzle 77. Accordingly, the fourth set of quat pegs 25 and the fifth set of quat pegs 27 may be configured as fuel injectors to route and/or inject a portion of the fuel into the airflow 67 upstream of the fuel nozzles 18 associated with the first fuel circuit 72. In this manner, the quat pegs 14 associated with the first fuel circuit 72 may be configured to change, or bias, the air/fuel ratio of the first fuel circuit 72 relative to the second fuel circuit 76 and/or the central fuel circuit 74. Furthermore, as noted above, varying the air/fuel ratio of the fuel nozzles 18 may decrease the combustion dynamics amplitudes and/or coherence and may therefore reduce unwanted vibratory responses within the combustor 12 and/or downstream components.

In some embodiments, the quat pegs 14 (e.g., one or more quat pegs 14 and/or one or more sets of quat pegs 14) may be arranged to bias fuel flow towards any of the fuel nozzles 18 and/or the fuel circuits (e.g., the second fuel circuit 76 and/or the central fuel circuit 74), such that the air/fuel ratio between the fuel circuits, and therefore the fuel nozzles 18, are different within and/or among the combustors 12. Further, in addition to varying the axial and circumferential configurations of the quat pegs 14 such that the quat pegs 14 bias the quat circuit fuel flow through certain fuel nozzles 18 and/or certain fuel circuits, in certain embodiments, the geometries of the quat pegs 14 may be different among each fuel nozzle 18 and/or each fuel circuit. For example, the size, shape and/or angles of the quat pegs 14 associated with the first fuel circuit 72 may be different from those associated with the second fuel circuit 76 or the central fuel circuit 74, such that the convective time and/or the air/fuel ratio between the fuel circuits, and therefore the fuel nozzles 18, may be different within and/or among the combustors 12.

FIG. 5 is cross-sectional schematic of an embodiment of the gas turbine system 10 of FIG. 1, taken along line 5-5, illustrating a plurality of combustors 12 each having a respective quat peg 14 configuration configured to control combustion dynamics and/or modal coupling of combustion dynamics, to reduce the possibility of unwanted vibratory responses in downstream components. In particular, it should be noted that each quat peg 14 configuration may include any variation technique (e.g., axial staggering, circumferential placement, and/or variations in size, shape, angles, etc.) and/or may include any combination of variation techniques. Each variation technique, either alone or in combination with other variation techniques, may be configured to help decrease combustion dynamics amplitudes and/or reduce coherence to reduce unwanted vibratory responses in downstream components within the system 10. Furthermore, the quat peg 14 configurations may be varied in different patterns or groupings within the system 10, as further described below.

In some embodiments, configurations of quat pegs 14 may bias the quat fuel towards one or more fuel circuits, such that adjacent combustors 12 have quat pegs 14 biasing fuel to different fuel circuits. For example, in the illustrated embodiment, a first configuration 70 of quat pegs 14 in the first combustor 17 are configured to bias quat fuel flow to the first fuel circuit 72, such that the fuel nozzles 73, 75, and 77 of the first combustor 17 have an air/fuel ratio that is biased differently from other fuel circuits of the first combustor 17. In addition, the quat pegs 14 of a second configuration 78 are arranged to bias quat fuel flow to the second fuel circuit 76, such that fuel nozzles 79 and 81 of the second combustor 21 have an air/fuel ratio that is biased differently from other fuel circuits of the second combustor 21. Moreover, the first configuration 70 of quat pegs 14 may be different than the second configuration 78 of quat pegs 14 in the second combustor 21, such that the first combustor 17 has different combustion dynamics frequencies relative to the second combustor 21, thereby decreasing coherence and reducing unwanted vibratory responses in the gas turbine system 10.

In some embodiments, geometries of quat pegs 14 may be varied between combustors 12, such that a particular combustor 12 has different combustion dynamics frequencies relative to at least one other combustor 12. For example, in the illustrated embodiment, the first configuration 70 of quat pegs 14 in the first combustor 17 includes a quat peg 14 shape (e.g., circular) that is different from the quat peg 14 shape (e.g., square) of a third configuration 80 of quat pegs 14 in a third combustor 83. In certain embodiments, the size of the quat pegs 14 may be varied between combustors 12. For example, a fourth configuration 82 in a fourth combustor 85 includes quat pegs 14 that are different in size compared to the quat pegs 14 of a fifth configuration 84 in a fifth combustor 87. Specifically, the quat pegs 14 of the fourth configuration 82 may be smaller in size, such that the ratio between the quat pegs of the fourth and fifth configurations 82, 84 may be approximately 1:1, 1.5:1, 2:1, 2.5:1, and so forth.

In some embodiments, in addition to a variation related to geometry, the configurations of quat pegs 14 (e.g., the third configuration 80 relative to the first configuration 70) may include variations related to axial staggering along various axes and/or circumferential positioning of the quat pegs 14 to bias quat fuel to other fuel circuits. In this manner, a combination of different parameters may be used to help decrease coherence and reduce unwanted vibratory responses in downstream components within the system 10. Furthermore, in certain embodiments, a particular combustor 12 may not have any variations in quat pegs 14 relative to other combustors 12 and/or may not have any quat pegs 14. For example, in the sixth configuration 86 in the sixth combustor 89, no quat pegs 14 are disposed within the combustor 89. In this manner, the sixth combustor 89 may have a combustion dynamics frequency that is different than the first combustor 17, the second combustor 21, the third combustor 83, the fourth combustor 85, and/or the fifth combustor 87.

In some embodiments, the system 10 may include one or more groupings (e.g., 1, 2, 3, 4, 5, or more) of combustors 12, where each group of combustors 12 includes one or more combustors 12 (e.g., 1, 2, 3, 4, 5, or more). In some situations, each group of combustors 12 may include identical combustors 12 that differ from one or more other groups of combustors 12 within the system 10. For example, a first group of combustors 12 may include identical combustors 12 having a first configuration of quat pegs 14, and a second group of combustors 12 may include identical combustors 12 have a second configuration of quat pegs 14. Further, the first configuration of quat pegs 14 may be different from the second configuration of quat pegs 14 in one or more ways, as described above (e.g., axial staggering, circumferential placement, and/or variations in size, shape, angles, etc). Accordingly, the first group of combustors 12 may produce a combustion dynamics frequency that is different from the combustion dynamics frequency of the second group of combustors 12 within the system 10.

Technical effects of the invention include reducing combustion dynamics and/or modal coupling of combustion dynamics (e.g., reduce unwanted vibratory responses in downstream components) in a gas turbine system 10 by varying the configuration of a plurality of injection pegs 14 (e.g., quat pegs 14) associated with one or more combustors 12 of the gas turbine system 10. The arrangement of a plurality of quat pegs 14 associated with a particular combustor 12 may alter the combustion dynamics, in a way to substantially reduce or eliminate any unwanted vibratory response of the combustor and/or components downstream of the combustors 12. For example, varying the configuration (e.g., placement, arrangement, position, location, etc.) of quat pegs 14 axially and/or circumferentially may facilitate the tuning of convective time for one or more quat pegs and/or the fuel-air ratio at the fuel nozzle 18 level, and may result in combustion dynamics frequencies that are different, spread out over a greater frequency range, or any combination thereof, relative to any resonant frequencies of the components in the gas turbine system 10, and/or the combustion dynamics of one or more of the other combustors 12 in the gas turbine system 10. In addition, varying the geometries of the quat pegs 14 (e.g., size, shape, angle, etc.) may introduce a variation in convective time between two or more quat pegs and/or the fuel-air ratio between two or more fuel nozzles 18, and therefore may help decrease combustion dynamics amplitudes, and/or modal coupling of the combustion dynamics, which may reduce unwanted vibratory responses within the combustor 12, and/or downstream components within the system 10.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. 

1. A system, comprising: a gas turbine engine, comprising: a first combustor having a first set of fuel nozzles and a first plurality of injection pegs, wherein the first plurality of injection pegs are disposed in a first configuration upstream of the first set of fuel nozzles, along a first fuel path, and the first plurality of injection pegs are configured to route a fuel to the first set of fuel nozzles; and a second combustor having a second set of fuel nozzles and a second plurality of injection pegs, wherein the second plurality of injection pegs are disposed in a second configuration upstream of the second set of fuel nozzles, along a second fuel path, and the second plurality of injection pegs are configured to route the fuel to the second set of fuel nozzles, and the second configuration has at least one difference relative to the first configuration.
 2. The system of claim 1, wherein the at least one difference is configured to reduce coherence between the first combustor and the second combustor by varying a first convective time of the first set of injection pegs relative to a second convective time of the second set of injection pegs.
 3. The system of claim 1, wherein the at least one difference is configured to vary combustion dynamics between the first combustor and the second combustor by varying a first ratio of an air-fuel mixture of the first set of fuel nozzles relative to a second ratio of the air-fuel mixture of the second set of fuel nozzles.
 4. The system of claim 1, wherein the at least one difference between the first plurality of injection pegs and the second plurality of injection pegs comprises a difference between at least one injection peg of the first plurality of injection pegs and at least one injection peg of the second plurality of injection pegs.
 5. The system of claim 4, wherein the at least one difference between the first plurality of injection pegs and the second plurality of injection pegs comprises at least one of a different axial configuration, a different circumferential configuration, or a different geometry, or any combination thereof.
 6. The system of claim 5, wherein the different axial configuration comprises at least one of a different axial placement, a different axial location, a different axial position, or a different axial arrangement, or any combination thereof, between one or more axes of the first or second combustor.
 7. The system of claim 5, wherein the different circumferential configuration comprises at least one of a different circumferential placement, a different circumferential location, a different circumferential position, or a different circumferential arrangement, or any combination thereof, between a first axis of the first and second combustor.
 8. The system of claim 5, wherein the different geometry comprises at least one of a different angle, a different size, or a different shape, or any combination thereof, between the first plurality of injection pegs and the second plurality of injection pegs.
 9. The system of claim 1, wherein the first set of fuel nozzles are arranged into one or more fuel circuits, and wherein a first injection peg and a second injection peg of the first plurality of injection pegs are associated with a first fuel circuit and a second fuel circuit of the one or more fuel circuits, respectively.
 10. The system of claim 9, wherein the first injection peg comprises at least one difference relative to the second injection peg, and wherein the at least one difference comprises a different axial configuration, a different circumferential configuration, a different geometry, or any combination thereof.
 11. A system, comprising: a first turbine combustor, comprising: a first plurality of fuel nozzles configured to route an air-fuel mixture to a combustion chamber of the first turbine combustor, wherein the first plurality of fuel nozzles comprises a first set of fuel nozzles and a second set of fuel nozzles; and a first plurality of injection pegs configured to route a fuel to the first plurality of fuel nozzles, wherein the first plurality of injection pegs comprises a first set of injection pegs associated with the first set of fuel nozzles and a second set of injection pegs associated with the second set of fuel nozzles, and the first set of injection pegs has at least one difference relative to the second set of injection pegs.
 12. The system of claim 11, wherein the at least one difference is configured to reduce coherence between the first combustor and the second combustor by varying a first convective time of the first set of injection pegs relative to a second convective time of the second set of injection pegs.
 13. The system of claim 11, comprising a second turbine combustor comprising: a second plurality of fuel nozzles configured to route the air-fuel mixture to a second combustion chamber of the second turbine combustor, wherein the second plurality of fuel nozzles comprises a third set of fuel nozzles and a fourth set of fuel nozzles; and a second plurality of injection pegs configured to route the fuel to the second plurality of fuel nozzles, wherein the second plurality of injection pegs comprises a third set of injection pegs associated with the third set of fuel nozzles and a fourth set of injection pegs associated with the fourth set of fuel nozzles.
 14. The system of claim 13, wherein the first set of injection pegs or the second set of injection pegs comprises at least one difference relative to the third set of injection pegs or the fourth set of injection pegs.
 15. The system of claim 14, wherein the at least one difference is configured to vary combustion dynamics between the first combustor and the second combustor by varying a first ratio of an air-fuel mixture of the first set of fuel nozzles relative to a second ratio of the air-fuel mixture of the second set of fuel nozzles.
 16. The system of claim 11, wherein the at least one difference between the first set of injection pegs and the second set of injection pegs comprises a different axial configuration, a different circumferential configuration, a different geometry, or any combination thereof.
 17. The system of claim 11, wherein the first set of injection pegs or the second set of injection pegs comprises a set of zero injection pegs.
 18. A method, comprising: controlling a first combustion dynamic of a first combustor or a first convective time of a first set of injection pegs of the first combustor with a first configuration of a first plurality of injection pegs disposed upstream of the first set of fuel nozzles along a first fuel path; and controlling a second combustion dynamic of a second combustor or a second convective time of a second set of injection pegs of the second combustor with a second configuration of a second plurality of injection pegs disposed upstream of the second set of fuel nozzles along a second fuel path, wherein the second plurality of injection pegs has at least one difference relative to the first plurality of injection pegs.
 19. The method of claim 18, wherein the at least one difference comprises a different axial configuration, a different circumferential configuration, a different geometry, or any combination thereof.
 20. The method of claim 18, wherein the at least one difference between the first plurality of injection pegs and the second plurality of injection pegs is configured to reduce modal coupling between the first combustor and the second combustor. 